RTTY Transmissions Off-freq with MMTTY

I participated in the NAQP RTTY contest this weekend. I normally use 2 radios in contests. In this one, I setup for RTTY and started the contest. Nobody could hear me with one radio (IC-7600) using an all-band dipole/doublet that normally works quite well for US contacts. The Radio was setup using N1MM+ with the common MMTTY RTTY Engine. I have used this several times in the past, and it worked well. Not this time.

I stopped and took a few minutes to see what the problem was. The other Radio, an FTDX-3000 was working fine. The difference between the radios is that one was using true FSK and the other was using AFSK from an internal sound card. The IC-7600 was using the AFSK, Since I only have the USB interface to the radio for RTTY, I cannot use the internal FSK demodulator. I finally discovered that my Transmit frequency was offset from the Receive frequency. To use AFSK, I set the Receive Tone frequency to 1445 Hz instead of the actual 2125 Hz used in true FSK. But when I would transmit, the Tone appeared to change to the default 2125 Hz, and I could see no way to change that setting.

I ran the contest with one radio for a while, but also pulled-up some MMTTY documentation. Buried far down in the document was a comment that you must turn ON the “NET” button in the dislayed MMTTY Engine screen if you are using AFSK and want to Transmit and Receive on the same frequency.   Well, I can’t imagine anyone using AFSK RTTY that would not want to do that, and I doubt that I ever changed that button setting (on purpose). So I clicked the button and got back to two radios.

The one benefit of this problem is that I took some time and read the MMTTY documentation. I also discovered that you can click and “grab” not only callsigns, but exchange information (Name and State/Province in this contest) using the mouse. That really speeds-up the RTTY contest QSOs.



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